1. Field of the Invention
The present invention relates generally to internal combustion engine systems, and more specifically, to a cam-driven radial rotary engine characterized by fuel air mixture compression with compression ignition, commonly referred to as Homogenous Charge Compression Ignition or HCCI.
2. Description of Related Art
HCCI engine systems are well known in the art. These engines may be viewed as a hybrid between traditional gasoline spark engines and diesel engines. Similar to a gasoline engine, and in contrast to a diesel engine, an HCCI engine operates on a pre-mixed charge of fuel and air. Unlike a traditional gasoline engine but similar to a diesel engine, an HCCI engine does not throttle air intake and uses the temperature created by compression to cause ignition of the fuel-air charge. This hybrid form of combustion has many benefits including increased efficiency and reduced emissions.
One of the problems commonly associated with HCCI engines is the variance of ignition timing as a function of fuel characteristics and engine operating condition. Other problems include a tendency to misfire when operating at low load with lean charge, and extreme pressure and ringing resulting from near simultaneous ignition of the entire fuel-air charge when operating at heavy load with a near stochiometric fuel-air charge. Therefore, there exists a need for a commercially viable HCCI engine capable of operating over a wide load range.
Opposed piston two stroke engines are well known in the art. These engines provide a mechanically simple engine, however, these engines have disadvantages. One disadvantage relates to difficulty in management of cylinder temperature and charge density resulting from intake and scavenge air sharing common passages to the intake port. A second disadvantage relates to difficulty in over-expansion of combustion gases resulting from gating of intake and exhaust ports by pistons. Therefore, there remains an opportunity to improve the opposed piston two stroke engine.
Rotary cam-driven radial engines are well known in the art and provide two key advantages: high power to weight ratio resulting from efficient cylinder packaging in a radial pattern; and the ability to better control piston movement and generate multiple power strokes per revolution due to the use of cams in place of crankshafts. This engine form also has two key disadvantages: difficulty in placing a spark plug or fuel injector in the combustion chamber in rotating cylinder forms of the engine; and speed limitations in all forms of the engine resulting from the high surface speed of the radial cam track. Conventional rotary cam-driven radial engines typically employ rotating cams and stationary cylinders to overcome the difficulty of installing ignition devices in rotating cylinders, but this precludes use of the more capable rotating cylinder form. Conventional rotary cam-driven engines also typically employ roller bearings as cam followers, but these bearings limit engine speed and power due to the high surface speed of the cam track.
Therefore, there remains an opportunity to improve cam-driven radial engines via an improved cam follower and by eliminating the need for a gasoline spark plug or diesel fuel injector having direct access to the rotating cylinder.
The integration of a permanent magnet motor/generator with an internal combustion engine for starting, generating electrical power, providing reverse rotation, aiding acceleration, and recapturing braking energy is common in prior art. However, motor/generators do not operate well in high temperature environments, therefore there exists a need to improve the integration of a motor/generator with internal combustion engines.
Accordingly, although great strides have been made in the area of internal combustion engines, many shortcomings remain.